Summary of Significant Accounting Policies - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassifications [Line Items]
Property operating expense	$ 41,737	$ 38,184	$ 83,556	$ 76,035
Gain on sales of properties	29,590	16,124	29,590	39,532
INCOME FROM CONTINUING OPERATIONS	$ 37,729	25,224	$ 46,908	57,070
Loss from discontinued operations		0		0
Gain on sales of properties		0		0
LOSS FROM DISCONTINUED OPERATIONS		0		0
As Previously Reported
Reclassifications [Line Items]
Property operating expense		38,184		76,018
Gain on sales of properties		16,124		39,527
INCOME FROM CONTINUING OPERATIONS		25,224		57,082
Loss from discontinued operations		0		(17)
Gain on sales of properties		0		5
LOSS FROM DISCONTINUED OPERATIONS		$ 0		$ (12)